Can You Learn Anything While You Sleep?

There are only 24 hours in a day, and usually about a third of that is spent sleeping. So, the overambitious have always wondered: Is it possible to make use of this time and learn a new skill or even a language? In other words, is sleep learning possible?

The answer is yes and no, depending on what we mean by “learning.”

Absorbing complex information or picking up a new skill from scratch by, say, listening to an audio recording during sleep is almost certainly impossible. But research shows that the sleeping brain is far from idle and that some forms of learning can happen. However, whether that’s worth losing sleep over has yet to be determined. [Why Can’t We Remember Our Dreams?]

Sleep learning: From sham to science

The concept of sleep learning, or hypnopedia, has a long history. The first study to demonstrate a memory and learning benefit from sleep was published in 1914 by German psychologist Rosa Heine. She found that learning new material in the evening before sleep results in better recall compared to learning during the day.

Thanks to many studies done since then, we now know that sleep is crucial for forming long-term memories of what we have encountered during the day. The sleeping brain replays the day’s experiences and stabilizes them by moving them from the hippocampus, where they are first formed, to regions across the brain. Given that so much is happening to memories during sleep, it’s natural to ask if the memories can be altered, enhanced or even formed anew.

One popular approach to sleep learning was Psycho-phone, a popular device in the 1930s. It played out motivational messages to sleepers, such as “I radiate love,” supposedly helping the people absorb the ideas in their subconscious and wake up with radiant confidence.

At first, it seemed that research backed up the idea behind devices like Psycho-phone. Some early studies found that people learned the material they encountered during sleep. But those findings were debunked in the 1950s, when scientists began to use EEG to monitor sleep brain waves. Researchers found that if any learning had happened, it was only because the stimuli had woken the participants. These poor studies launched sleep learning into the trash can of pseudoscience.

But in recent years, studies have found that the brain may not be a total blob during sleep. These findings suggest that it is possible for the sleeping brain to absorb information and even form new memories. The catch, however, is that the memories are implicit, or unconscious. Put another way, this form of learning is extremely basic, much simpler than what your brain has to accomplish if you want to learn German or quantum mechanics.

Still, these findings have elevated sleep learning from the category of pipe dreams and put it back on scientists’ radar.

“For decades the scientific literature was saying sleep learning was impossible. So, even seeing the most basic form of learning is interesting for a scientist,” said Thomas Andrillon, a neuroscientist at Monash University in Melbourne, Australia. “But people are not really interested in this basic form of learning.”

For scientists, the recent discoveries have raised hopes about possible applications, Andrillon told Live Science. For example, the implicit nature of sleep learning makes the phenomenon useful for people who want to shed a bad habit, like smoking, or form new good ones. [Why Is It So Hard to Quit Smoking?]

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